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What Vitamin D Does For Your Body, Say Experts

Here's what vitamin D does for your body.

Vitamin D has gotten a lot of attention in recent years. That's because many of us don't get enough of the "sunshine vitamin," so named because our bodies produce it naturally in response to sunlight (which is why so many of us are deficient). Additionally, research has found that adequate vitamin D levels may have wide-ranging health benefits, from how well our body's basic systems operate to how long we live. Here's what vitamin D does for your body, according to the experts. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs COVID is Hurting You—Even After a Negative Test.


Vitamin D May Help You Live Longer

vitamin d in the sun

According to a study published in the Journal of Nutrition, vitamin D may lengthen your telomeres, the parts of cells that hold DNA information and serve as the biological markers of aging. (Telomeres shorten as we get older, and when they get too short, a cell dies.) Researchers found that middle-aged adults who had higher blood concentrations of vitamin D had longer telomeres. A 2021 review of studies reached the same conclusion, saying vitamin D supplementation may have "potentially beneficial effects … on aging and age-related diseases."

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Vitamin D May Reduce Your Cancer Risk

Shot of woman nutritionist doctor writes the medical prescription for a correct diet on a desk with fruits, pills and supplements.

Some studies have found that vitamin D deficiency is associated with an increased risk of several types of cancer, including breast, colon, prostate, leukemia, lymphoma and melanoma. However, the data is mixed. One review of studies found out that higher vitamin D levels didn't reduce the risk of stomach, prostate or esophageal cancer, but may reduce the risk of colon cancer, while a 2021 review of studies found "no statistically significant effective of vitamin D on breast cancer."

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Vitamin D May Protect Against COVID-19

Woman wearing protective face mask in the office

Early in the pandemic, eyebrows were raised when a Spanish study found 82% of hospitalized COVID patients were deficient in vitamin D, indicating that the vitamin may be protective against the coronavirus. Those findings have held up, and other studies have found vitamin D may even protect you against catching COVID: According to a December 2021 meta-analysis of 54 studies published in Frontiers in Public Health, vitamin D insufficiency and deficiency is associated with a higher risk of COVID infection, hospitalization, ICU admission and death.  

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Vitamin D Improves Bone Health

Digital composite of Highlighted leg bones of jogging woman on beach

Little-known fact: Our bones are constantly breaking down and rebuilding themselves. That makes Vitamin D a vital nutrient. It helps the body absorb calcium, which is essential for bone formation. "Getting enough calcium and vitamin D in your diet can help maintain bone strength and lessen your risk of developing osteoporosis," says the National Institutes of Health.

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Vitamin D Helps Regulate Your Immune System

woman getting her vitamin D outside

Vitamin D supports the immune system by helping white blood cells function. It also helps to regulate the immune system's response so it doesn't become overactive. Vitamin D may also play a role in reducing the risk of autoimmune conditions such as multiple sclerosis, type 2 diabetes and lupus. 

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How Much Vitamin D Do You Need? 

vitamin d

About 40% of Americans are deficient in Vitamin D. The Office of Dietary Supplements recommends adults consume 600 IU of vitamin D daily between food and supplements. (However, this recommendation is controversial, and many experts say that should be higher.)

Vitamin D is found in foods like salmon, egg yolks, mushrooms and fortified milk, juice and cereals. However, it can be difficult to difficult to get all the vitamin D you need from food, so supplementation may be necessary. A word of caution: Vitamin D is a fat-soluble vitamin, meaning excess amounts are stored in the body. Taking too much can be toxic (although that's a rare occurrence). It's a good idea to get your doctor's advice before beginning any supplement. And to live your healthiest life, don't miss this life-saving advice I'm a Doctor and Here's the #1 Sign You Have Cancer.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael